Selective Adsorbent Purification of CFC-113 Isomers
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Solution Overview
Problem
The separation of structural isomers CFC-113 and CFC-113a by distillation is challenging due to their similar boiling points, and their presence in reactions can lead to the formation of undesirable by-products, such as CFC-1112a and CFC-1122, which are difficult to separate from chlorotrifluoroethylene (CTFE).
Innovation Solution
A method involving the use of a selective adsorbent, such as carbon, nickel, or copper, to preferentially adsorb CFC-113a from a mixture with CFC-113, reducing its concentration by more than 7% within 24 hours, and potentially to less than 0.1 weight percent, facilitating the separation of these isomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to separate CFC-113 and CFC-113a, then separation is attempted, but the separation is difficult due to similar boiling points (differ by only 1.3 degrees Celsius)
Solution Approach 1:
The patent changes the separation mechanism from thermal-based (distillation relying on boiling point differences) to adsorption-based (relying on selective adsorbent interaction). This parameter change in the separation mechanism allows effective separation of isomers with similar boiling points by exploiting differences in their adsorption characteristics on selective adsorbents.
Solution Approach 2:
The patent introduces a selective adsorbent as an intermediary substance that preferentially interacts with CFC-113a over CFC-113. This intermediary enables separation by forming a temporary complex or adsorption state that distinguishes between the two isomers, allowing for effective separation despite their similar physical properties.
2Productivity
If CFC-113a is present in the reaction with hydrogen or metals to produce CTFE, then the reaction proceeds, but undesirable by-products (CFC-1112a and CFC-1122) are formed which are difficult to separate from CTFE by distillation
Solution Approach 1:
The patent applies preliminary action by removing CFC-113a from the mixture before the CTFE synthesis reaction occurs. This preventive measure eliminates the source of harmful by-products (CFC-1112a and CFC-1122) that would otherwise form during the reaction, ensuring higher product purity without requiring complex post-reaction separation.
Solution Approach 2:
The patent applies preliminary anti-action by using selective adsorbents to counteract the presence of CFC-113a before it can participate in unwanted side reactions. This preemptive removal prevents the formation of harmful by-products that would be difficult to separate, thereby protecting the main reaction from producing undesirable compounds.
3Manufacturing precision
If selective adsorbents are used to preferentially adsorb CFC-113a, then the concentration of CFC-113a is reduced by more than 7% within 24 hours, but the contact time required for effective separation increases
Solution Approach 1:
The patent employs porous adsorbent materials with specific pore structures that enhance the adsorption capacity and selectivity for CFC-113a. The porous structure provides increased surface area and optimized interaction sites, allowing for more rapid and efficient separation that reduces the required contact time while maintaining high separation purity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively reduces the concentration of CFC-113a in the treated composition, enabling more efficient separation and preventing its conversion to undesirable by-products during the production of chlorotrifluoroethylene (CTFE), thus improving the purity and yield of CTFE production.
Implementation Method 1
contacting the untreated composition with a selective adsorbent to preferentially adsorb 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a)
Data Source
AI summary
A method of separating 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) includes providing an untreated composition including 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a). The untreated composition is treated with an adsorbent to form a treated composition in which the concentration of 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) is less than 93 percent of the concentration of the 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in the untreated composition based on a treatment time of 24 hours.